The invention relates to an arrangement for producing high hydraulic pressures, in particular for actuating a hydraulic press.
When generating and controlling high pressures, for instance above 400 bar, the local fluid heating at constrictions and throttle points, such as directional control valves, is very great and the wear at the throttle edges high. Also, the hydraulic amplification in valves with throttle edge control is very high and consequently pressure control systems tend to oscillate at such high pressures.
It has therefore already been proposed for the controlling of high pressures that the high pressure for the load or consumer be generated with a pressure intensifier or transmitter which has a differential piston and that the control or regulation of the pressure be carried out on the low-pressure side; this eliminates the valves on the high-pressure side. A disadvantage is however the necessary size of the pressure transmitter or intensifier, the high-pressure-side displacement of which must be made large enough to ensure that the displacement is always adequate for the consumer or load. It is assumed here that the fluid flow to the consumer must not be interrupted. This is for example the case in a press plant in which chemical-physical reactions are taking place. If after closure of the press mould or die by means of a conventional hydraulic system a predetermined pressure is reached then a predetermined pressure curve must be followed which requires a relatively slow pressure increase, whereupon a predetermined end pressure must be kept constant for a certain time; this operation can last a long time. Thereafter there is a slow pressure decrease until the press mould can be opened.
The problem underlying the invention resides in further developing the arrangement of the type outlined at the beginning so that very high pressures can be generated and exactly controlled. In particular, predetermined pressure values are to be generated in the form of pressure curves without any pressure collapses or discontinuities of the pressure.